A naturally occurring inhibitor of catecholamine-induced free fatty acid mobilization is being investigated in terms of its effect on serum lipids. The inhibitory substance has been isolated from the dog hypothalamus and from the calf mid-brain (the area in which the hypothalamus is located). The hypothalamus is of major importance in metabolic processes and contains centers vital to fat metabolism and transport. We plan to study the inhibitor in two mammalian species--the dog and rat. Experiments have been designed to study the effect of the inhibitor on the synthesis of blood lipid components such as cholesterol and triglycerides by measuring levels of enzymes involved in their synthesis. The levels of these lipid fractions have been associated with the development of coronary heart disease. It is through the study of factors affecting lipid mobilization one can expect to determine what regulates the metabolism of compounds like cholesterol and triglycerides that are not only essential to health, but also, are factors involved in the development of atherosclerotic lesions.